14 - Drought in Costa Rica

Droughts in Costa Rica – time space behaviour,
trends and links to atmospheric circulation pattern
Christian Birkel1 & Siegfried Demuth1,2
1Institute
of Hydrology, University of Freiburg, Germany
2IHP/HWRP
Secretariat, Koblenz, Germany
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Objectives:
to describe temporal and spatial behaviour of droughts
and drought risk
to investigate trends in streamflow drought series
to analyze relationships to atmospheric drought patterns
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Study area
17 gauging Stations,
Records: 11 stations; 1973 – 2003
Atlantic
watershed:
The Northern
Zone and the
Caribbean.
6 stations > 20 years
Pacific watershed: The North Pacific
region, the Central Valley, the Central
and South Pacific region.
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Drought event definition
daily streamflow
non-seasonal fdc
seasonal fdc
low flow seasonal fdc
fdc for the wholeyear register
high flow seasonal fdc
fdc for the station
specific defined
low flow season
fdc for the station
specific defined
high flow season
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Drought Indices
Non-seasonal Q90, Q70 and high and low flow
seasonal Q90, Q70 threshold levels:
Annual Maximum Duration
AMD
Annual Cumulated Duration
ACD
Annual Maximum Deficit Volume
AMV
Annual Cumulated Deficit Volume
ACV
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Temporal drought behaviour
Dry season (low flow season): Single, long droughts (AMD) with
relatively low deficit volume (AMV).
Rainy season (high flow season): Multiple, short events (AMD) of
important deficit volume (AMV).
station
Guatuso
climatic region threshold Mean AMD Mean AMV Mean ND
35.6
127.1
1.20
Northern Zone Q90 annual
40.5
194.1
1.33
Q70 LF
Q70 HF
20.1
367.9
2.65
Guardía
North Pacific
Q90 annual
32.2
142.3
0.79
39.2
220.0
0.96
Q70 LF
Q70 HF
17.9
180.6
1.67
Tacares
Central Valley Q90 annual
27.5
132.9
1.16
42.6
252.9
1.29
Q70 LF
23.4
384.0
1.00
Q70 HF
28.3
94.7
1.35
Londres
Central Pacific Q90 annual
28.3
94.7
1.35
Q70 LF
15.3
275.3
1.16
Q70 HF
25.9
94.3
1.60
Caracucho South Pacific Q90 annual
34.4
138.9
1.73
Q70 LF
Q70 HF
28.0
571.8
1.77
Pandora
Caribbean
Q90 annual
20.9
104.5
1.93
Q70 LF
34.1
267.8
1.87
Q70 HF
18.3
420.2
2.70
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Spatial drought behaviour AMD (1973-2003)
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Spatial drought behaviour:
Drought threat
Probability P
{at least one occurrence of a
T - year event in N years}
P=1–[1–1/T]N
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Spatial Drought behaviour :
Drought threat
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Non-parametric Mann-Kendall trend test (1973-2003)
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Link to atmospheric circulation pattern
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Conclusions
Global, regional and local scaled influences
directly affect Costa Rican drought
development
clear spatial distinction in Pacific/Atlantic
watershed and north/south border
one significant positive trend
strong relationship with atmospheric
circulation patterns
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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Conclusions
Rainy season plays a very important role on temporal and
regional drought development.
Streamflow drought is a regional phenomenon and uses
to expand its impact into regions, which are normally not
considered to be affected by drought as e.g. the Northern
Zone and the Caribbean.
Influences on drought development in Costa Rica as e.g. by
global (ENSO, NAO, etc.) and regional (ITCZ) atmospheric
circulations, physiography (e.g. Hydrogeology) and
anthropogenic factors (e.g. water supply, reservoirs, water
extractions, etc.) were identified and might be usefully
implemented in an early warning system.
5th International FRIEND Conference, 27 November - 1 December 2006, Habana, Cuba
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